html,body{
    height: 100%;
    margin: 0;
    padding: 0;
}
.window_boundingBox{
    position: fixed;
    border:1px solid #000;
    box-shadow: 0 0 12px rgba(0,0,0,.5);
    background-color: #fff;
}
.window_header{
    background-color: #333;
    color: #fff;
    text-align: center;
    padding: 5px;
    font-size: 20px;
}
.window_body{
    padding: 10px;
}
.window_footer{
    position: absolute;
    bottom: 0;
    padding-bottom: 10px;
    text-align: center;
    width: 100%;
}
.window_cancelBtn{
    margin-left: 20px;
}
.window_alertBtn{
    width: 100px;
    position: absolute;
    bottom: 10px;
    left: 50%;
    margin-left: -50px;
}
.window_closeBtn{
    position: absolute;
    right: 0;
    top: 0;
    padding: 5px 10px;
    font-size: 20px;
    background-color: blue;
    color: #fff;
    cursor: pointer;
}
.window_mask{
    width: 100%;
    height: 100%;
    background-color: #000;
    opacity: .3;
    position: absolute;
    left: 0;
    top: 0;
}


/* window_skin_a */ 
.window_skin_a .window_header{
    background-color: red;
}